Ventilating system



Patented Oct. 21, 1941 VENTILATING SYSTEM Kenton D. McMahon, Scotia, N. 1., trainer to General Electric Company, a corporation of New York Application January 18, 1940, Serial No. 314,453

4 Claims.

The present invention relates to ventilating systems in which air is circulated through'ducts by a motor driven centrifugal fan.

The object of my invention is to provide in ventilating systems of this type an improved construction and arrangement for housing and cooling the fan driving motor, and for a consideration of what I believe novel and my invention, attention is directed to the following description and the claims appended thereto.

In the accompanying drawing, Fig. 1 is a sectional side elevation of the ventilating system, and Fig. 2 is a front elevation of the ventilating system. 1

Referring to the drawing, there is shown a centrifugal fan casing I having an inlet orifice 2 connected to a duct 3 and having an outlet 4 connected to a duct 5. The fan casing is supported on a base 8 by standards 1 and 8 fixed respectively to the end walls 8 and III of the casing. Fixed to the standard 8' is a supporting ring H fitting in an opening He in the standard 8 and into an opening l2 in the casing end wall I0. Supported on the ring H is a cup-shaped motor casing l3 having one end welded to a ring which is bolted to the supporting ring H and having the other end welded to a ring I! to which is fixed an end cap it. The joints between the supporting ring I I and the opening l2 in the fan casing, between the ring l4 and the supporting ring H, and between the ring I! and the end cap it are air-tight. This construction accordingly provides a chamber within the casing l3 sealed to the fan casing around the edges of the opening l2.

Within the casing I 3 is an electric motor comprising a stationary member ll and a rotating member l8 having a shaft is extending through the supporting ring H into the opening I2 in the fan casing. The shaft is journaled in bearings and 2i fixed to end frames 22 and 23 on the stationary member I1. 'The motor is resiliently supported by rubber rings 24 and 25 surrounding hubs 26 and 21 on the motor end frames 20 and 2|. The rubber ring 24 is clamped between rings 28 and 28 fixed to the hub 28 and is squeezed radially outward into engagement with a concave surface 30 on the supporting ring II, as described more fully in my application Serial No. 301,416, filed October 26, 1939. The rubber ring 25 is clamped between rings 3| and 32 flxed to I the hub 21 and is squeezed radially outward into engagement with a concave surface 33 on the ring l5. By varying the compression of the rings 28 and 29 and of the rings 30 and 3|, the

On the motor shaft I9 is a centrifugalfan impeller having a hub 34 fixed thereto. On the front side of the hub 34 are blades 35 for circulating the main air stream through the ducts- 3 and 4. The front or inlet ends 38 of the blades project within the inlet orifice 2 of the fan casing and the outlet edges 31 of the blades discharge to the fan casing. Fixed to the front ends of the blades is a shroud. ring 38 which holds the blades together and also serves to di-' rect air from the inlet to the outlet edges of the blades. A seal between the inlet orifice 2 and the shroud ring 38 is provided by flanges 39 and 40 respectively on the inlet oriflce and on the shroud ring.

On the rear side of the hub 34 is a flange 4| which cooperates with a flange 42 on the supporting ring II to provide a seal between the fan casing l and the motor casing l3. From one aspect the hub 34 forms a closure for the opening between the fan casing and the motor casing. The seal provided by the in fitting annular flange 4| and 42 is not air tight. It is, however, sufficient to keep particles of dirt, water droplets and the like, which might be entrained in the main air stream within the fan casing, from reaching the motor casing H.

The motor is cooled by air currents circulated within the casing l3 by blades 43 mounted on the rear side of the hub 34 or, in other words, on the side of the hub adjacent the motor. The blades 43 draw air through openings 44 in the motor end frame 22 and through openings 4|! in the supporting ring II, and discharge the air through openings 48 in the supporting ring H .into an annular passage 41 surrounding the motor and defined by the motor casing 13 and a band 48 wrapped around the stationary member I! of the motor. From the passage 4! the air flows to the interior of the motor through openings 48a in the end frame 23. The air is circulated within the motor by blades 49 and 50 fixed to the rotating member I 8. The air flowing through the openings 48a is guided to the intake edges of the blades 43 by a conical bailie 5| fixed to the end frame 23. The blades 49 force air around the stationary member ll of the motor through a passage 52 between the stationary member and the outside of the conical bafile 5| and through a passage 53 between the stationary member ll and the band 43. The passage 53 terminates within the end frame 22, from which the air is drawn by the blades 43. The blades 50 circulate air with the end frame 22, as indicated by the arrow 54. By this arrangement the motor is cooled by air circulated within the motor casing l3 by the blades 43 on the rearslde of the fan hub 34. In circulating over the motor, the heat generated in the motor is transferred tothe air. In passing through the blades 43, the heat of the motor cooling air is transmitted to the blades 43 and to the fan hub 34, and from the hub 34% to the fan blades 35, whence it is dissipated to the main air stream circulated through the ducts 3 and 5 by the blades 35, Since the blades 35 are moving a relatively large quantity of air compared to the air required to cool the motor, the heat transmitted from the motor does not objectionably raise the temperature of the main air stream circulated by the blades 35.

In the above described construction, the motor is sealed to the ducts of the ventilating system preventing the leakage of objectionable fumes into or out of the ducts. This is important. where air containing objectionable fumes is to be circulated through ducts passing through clean air or where clean air is to be circulated through ducts passing through an atmosphere containing objectionable fumes. Heretofore in such situations a totally enclosed electric motor has been used and the leakage into or out of the fan and motor casings has been prevented by packing or stufiing boxes. In the present construction the packing or. stufiing boxes are eliminated and a standard open type electric motor is used. The open type motor is much cheaper than the totally enclosed motor. The advantages of the prior construction using a totally enclosed elec-" tric motor are obtained in the present construction at a lower cost. Furthermore, the present construction permits the use of a noise reducing rubber mounting for the motor and fan. -The present construction is, therefore, cheaper, due to the use of an open type electric motor, quieter, due to the rubber mounting, and more reliable, due to the elimination of stuffing boxes.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a ventilating system, a centrifugal fan casing having inlet and outlet ducts, an opening in onesideof the casing, a motor, enclosing casing sealed to said fan casing around said opening providing a chamber sealed from the outside air, a motor in said chamber, an impeller having a hub closing said opening, blades on the side of the hub adjacent the chamber having intake and discharge ends within said chamber so as to circulate air over the motor, and blades on the opposite side of the hub for circulating air through the ducts.

2. In a ventilating system, a fan casing having inlet and outlet ducts,walls defining a motor enclosing casing sealed from the outside air, an opening in said walls defining a passageway leading from the interior of the motor casing to the interior of the fan casing, a motor in the motor casing, a fan having a hub closing said opening, blades on the side of the hub facing the motor casing having intake and discharge ends within the motor casing so as to circulate air over the motor, and blades on the opposite side of the hub for circulating air through the ducts.

3. In a ventilating system, a fan casing having inlet and outlet ducts, walls defining a motor enclosing casing sealed from the outside air, an opening in said walls defining a passageway leading from the interior of the motor casing to the interior of the fan casing, a motor in the motor casing having a shaft extending into said opening, means resiliently supporting the motor in its casing, a fan having a hub on the shaft, blades on the side of the hub facing the motor casing having intake and discharge ends within the motor casing so as to circulate air over the motor, and blades on the opposite side of the hub for circulating air through the ducts.

4. In avventilating system, a fan casing having inlet and outlet ducts, walls defining a motor enclosingcasing sealed from the outside air, an opening in said walls defining a passageway leading from the interior of the motor casing to the interior of the fancasing, a motor in the motor casing, a fan having a hub closing said opening, interfitting annular surfaces on the hub and one of said casings providing a seal between the fan and motor casings, blades on the side of the hub posite side of the hub for circulating air through the ducts.

KENTON D. McMAHAN. 

